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Biomedical subjects

A Marín

Publications and source records attributed to A Marín.

At least 19 recordsLinked to original sources
PubMed1991

Semiquantitative determination of serum IgE by reagent strips: PRIST/TOTALE correlation.

Due to its great simplicity, the determination of total and specific IgE with a reagent strip could be a screening method for in vitro allergy diagnosis if a correlation with classical techniques is verified. The TOTALE reagent strip for semiquantitative determination of total serum IgE is one of these methods and unites the now classical foundation (anti-IgE/IgE/anti-IgE labeled sandwich) and the ease of the reagent strip technique. In a preliminary evaluation of these methods we compared the PRIST isotopic method to the TOTALE one for serum total IgE. In summary, the most relevant consequences from this comparison are the following ones: a) The initial sample is the same for both: serum. b) No additional equipment or materials other than the serum sample are needed for TOTALE practising. c) The reagent strip has a lower cost and is faster than the PRIST method. d) Correlation coefficients were 0.89 (n = 35) in the range of measurement under study and 0.93 (n = 23) in the range from 5 to 200 U/L.

Child↗
PubMed1991

Comparison of the activity of imipenem and beta-lactams combined with sulbactam and clavulanic acid in beta-lactamase-producing strains of Bacteroides fragilis.

We compared the "in vitro" activity of imipenem with 14 beta-lactams, both alone and in combination with clavulanic acid, and sulbactam against 110 beta-lactamase-producing strains of Bacteroides fragilis. The following antibiotics were tested: amoxycillin, penicillin, mezlocillin, piperacillin, cephalothin, cephazolin, cefamandole, cefmetazole, cefonicid, cefoxitin, cefotaxime, ceftazidime, ceftizoxime, and ceftriaxone. In all cases, except those of cefoxitin and cefmetazole, these combinations showed a statistically significant increase in beta-lactam activity, which was, however, never higher than that of imipenem, the antibiotic which performed best against Bacteroides fragilis.

Anti-Bacterial Agents↗
PubMed1990

The general stochastic model of nucleotide substitution.

DNA sequence evolution through nucleotide substitution may be assimilated to a stationary Markov process. The fundamental equations of the general model, with 12 independent substitution parameters, are used to obtain a formula which corrects the effect of multiple and parallel substitutions on the measure of evolutionary divergence between two homologous sequences. We show that only reversible models, with six independent parameters, allow the calculation of the substitution rates. Simulation experiments on DNA sequence evolution through nucleotide substitution call into question the effectiveness of the general model (and of any other more detailed description); nevertheless, the general model results are slightly superior to any of its particular cases.

Animals↗
PubMed1990

Chloroplast genes transferred to the nuclear plant genome have adjusted to nuclear base composition and codon usage.

During plant evolution, some plastid genes have been moved to the nuclear genome. These transferred genes are now correctly expressed in the nucleus, their products being transported into the chloroplast. We compared the base compositions, the distributions of some dinucleotides and codon usages of transferred, nuclear and chloroplast genes in two dicots and two monocots plant species. Our results indicate that transferred genes have adjusted to nuclear base composition and codon usage, being now more similar to the nuclear genes than to the chloroplast ones in every species analyzed.

Base Composition↗
PubMed1990

[Intestinal polyps in childhood].

From 1965 to 1987, 230 polypectomies were performed in patients between 8 month to 16 years old, 147 boys and 83 girls. The most frequent symptom was rectal bleeding and the most frequent location was the rectosigmoid (96%). The polyps measured from 0.8 to 2 cm., in only one case the polyp measured more than 5 cm. causing duodenal obstruction and it was associated with a gastric polyp. Solitary polyps represented 93.9% of all cases, Peutz-Jeghers syndrome 1.73 and juvenile polyposis 0.87%. In that period 3 cases of colonic carcinoma in children over 9 years old were diagnosed. The histology of 200 polyps were reviewed. In 21 cases the diagnosis was modified (10.5%). The juvenile polyp (J.P.) was the most frequent type (93%). The usual histopathological pattern was observed in 71.5% of the J.P., early lesions (26.3%) and hyperplastic changes (2.1%). Six cases were tubular adenoma and one tubulovillous. The multiple juvenile polyposis was found in girls (13 and 14 years old). None of the patients with Peutz-Jeghers syndrome had gonadal tumor. Endoscopic polypectomy in children is a safe and effective treatment for colorectal polyps. This study provides information on the clinicopathologic findings in argentinian children with intestinal polyps treated by polypectomy over a 22 year period. It emphasizes that juvenile polyps is the most frequent pattern however other lesions can be present in gastrointestinal tract and also associated with others tumors. Patients with polyps should be followed at regular intervals which can be modified according to the histologic type and family history.

Adenoma↗
PubMed1989

Variation in G + C-content and codon choice: differences among synonymous codon groups in vertebrate genes.

The relationship between G + C-content and codon usage in genes of human, mus, rat, bovine and chicken nuclear genomes was investigated. Correlation and lineal regression analyses were carried out on plots that related the frequency of each codon within each synonymous codon group to the G + C-content of the coding sequence as a whole. Under GC pressure, in most of the quartet codon groups there is a preferential choice of the C-ending codon, except in leucine and valine codon groups where the choice of the G-ending codon is preferred. Among ducts, the choice of codons specifying phenylalanine and glutamate shows the strongest dependence on G + C-content. The relationship found between G + C-content and codon usage in these genomes correlate with taxonomic distance.

Animals↗
PubMed1989

[Significance of the presence of mastocytes in bronchoalveolar lavage in the diagnostic evaluation of diffuse interstitial lung diseases].

The cell preparations of 199 bronchoalveolar lavages (BAL) were reviewed to evaluate the meaning of the presence of mastocytes for the diagnosis of diffuse interstitial lung diseases. The study population consisted of 41 control individuals, 10 with extrinsic allergic alveolitis (EAA), 55 with sarcoidosis 38 with asbestosis, 25 with pulmonary fibrosis associated to collagen diseases, 18 with idiopathic pulmonary fibrosis and 12 with carcinomatous lymphangitis. Mastocytes were predominantly found in patients with EAA (8 of 10 cases) and in some cases of sarcoidosis and idiopathic pulmonary fibrosis. The rate of mastocytes in the patients with EAA was significantly higher than in the other groups (p less than 0.001). The presence of mastocytes in the BAL is particularly suggestive of EAA; rates higher than 3% are only found in this condition.

Alveolitis, Extrinsic Allergic↗
PubMed1989

SDSE: a software package to simulate the evolution of a pair of DNA sequences.

An algorithm to simulate DNA sequence evolution under a general stochastic model, including as particular cases all the previously used schemes of nucleotide substitution, is described. The stimulation is carried out on finite, variable length, DNA sequences through a strict stochastic process, according to the particular substitution rates imposed by each scheme. Five FORTRAN programs, running on an IBM PC and compatibles, carry out all the tasks needed for the simulation. They are menu driven and interfaced to the system through a principal menu. All sequence data files used and generated by the SDSE package conform to the standard GenBank database format, thus allowing the use of any sequence retrieved from this databank, as well as the application of other packages to analyse, manipulate or retrieve stimulated sequences.

Algorithms↗
PubMed1989

[Evaluation of in vitro adhesion of cariogenic microorganisms to enamel and dental filling materials].

The adhesive ability of Lactobacillus, Streptococcus mutans and Actinomyces viscosus-naeslundii on enamel, amalgam and composite of microparticle and small-particle are studied "in vitro". The selective mediums used for the three micro-organisms are, respectively, Rogosa agar, M.S.B. and C.F.A.T. The lower adherence is showed by bacterias of Lactobacillus genus. S. mutans and A. viscosus-naeslundii show similar adherence properties between them. The greatest adherence was obtained in composites, being S. mutans the bacteria with a greatest level of adherence to the composites of small-particle, and A. viscosus-naeslundii the bacteria with more adherence to the ones of micro-particle. The adherence on amalgam was slightly lower than the adherence on enamel.

Actinomyces↗